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Spartan6 critical warning on PLL (wizard generated)

In my project I'm using a xc6slx9 with ISE 14.7. I generated a PLL using the Wizard. During the implementation the following critical warning message is displayed. Despite of this message, the Implementation and Bitstream generation are completed without problems.

What I shoud do? Shoud I ignore the message, or there is a way to correct the problem?